The building materials and products whose content of natural radionuclides are contributors to the radiation exposure of the population. In this study several types of building materials used for construction of living buildings in Slovakia were examined. The concentrations of natural radionuclides (226Ra,232Th and40K) were determined by -ray spectrometry with an HPGe detector. In the second part of the work, sixty samples of building products (panel), used for dwelling construction in several towns in Slovakia, were analysed. The concentration of natural radionuclides and the radium equivalent activity content in the inner-and outerside of the wall were estimated. The results were used for the calculation of the annual mean effective photon dose rates, by the model and calculation procedure of KRISIUK and KARPOV.
Authors:S. Topcuoĝlu, K. Güven, R. Küçükcezzar, D. Kut, and N. Esen
Cesium-137 concentrations in red, brown and green algae have been studied for the calculation of natural depuration rates. The algae species were collected from the same population of the Black Sea stations during the period of 1986–1995. The natural depuration rates are estimated as biological half-lives. The pattern of depuration results represented by a single component for each algae division. The biological half-lives of137Cs in red (Phyllophora nervosa), green (Chaetomorpha linum) and brown (Cystoceira barbata) algae are estimated to be 18.5, 21.6 and 29.3 months, respectively.137Cs and40K activity levels and their ratios in algae species in two stations in Black Sea region of Turkey have been determined during the period of 1990–1995. The results showed that the Sinop region was more contaminated than the ile region on the Black Sea coast of Turkey from the Chernobyl accident.
The present paper deals with the following questions: Can a piece of any tissue or organ obtained at autopsies and/or biopsies be analyzed to predict the organ and/or body burden, initial exposures, and the committed dose equivalents to the workers or retired workers from exposures to thorium, uranium, and plutonium and what are the consequences of using such materials in predicting the initial exposures and the dose estimates? Based on the studies of the distribution of uranium and thorium in former uranium miners and millers, the distribution of plutonium in general population, and several other studies dealing with the distribution of actinides in man, it is reasonable to state that the utilization of tissue analyses for estimating the initial exposure to the workers may have serious limitations. The regulatory agencies must restrict the conditional utilization of tissue analyses in estimating exposures to the workers for thorium, uranium, and plutonium.
Authors:V. Spate, M. Mason, C. Reams, C. Baskett, J. Morris, and D. Mills
In this study we report on the comparison between the total selenium in serum (total Se) with that which is apparently bound to high molecular weight (>12,000 D) species, presumably proteins (bound Se). Nine hundred seventy seven (977) serum samples arising out of a population-based epidemiological study were prepared in duplicate for the determination of total Se by pipeting directly into irradiation vials; and separate duplicate aliquots were dialyzed against DI water for the determination of bound Se. All samples were analyzed by neutron activation analysis via77mSe (17.4 s). A small dialyzable Se component (6%) (free Se), defined as the difference between the total Se minus the bound Se, was identified.
Authors:S. Sarmani, A. Wood, Z. Hamzah, and A. Majid
The aim of this study is to investigate the contents of toxic and essential trace element such as As, Hg, Se and Zn by neutron activation analysis in coastal fishes consumed by the general population of Malaysia. The mean values of the elements analysed expressed in mg/kg fresh weight ranged 1.42–5.61, 0.06–0.42, 4.2–20.6, 0.41–1.28 for As, Hg, Zn and Se, respectively. The maximum permissible limit for As in food was set at 1.0 mg/kg under the Malaysian Food Regulations. Our results showed that consumption of coastal fishes is not permitted under the regulations, while the levels of Hg, Se and Zn were within the permissible limits. The daily dietary intake of As and Hg at 400 g and 30g respectively are still within the tolerance levels.
Data are presented for210Po levels in edible parts of marine species significant in the diet of the Argentine population. The sample collection sites were situated between 35° and 45° S in the Atlantic Ocean. The specific activities obtained, expressed per wet veight and with a 95% confidence level, ranged between 31.3±9.1 mBq kg–1 for pollack (Genypterus blacodes) and 1790±280 mBq kg–1 for squid (Illex argentinus). Hake (Merluccius hubbsi) followed by squid are the major contributors to the dose. The annual committed effective doses were 0.7 mSv and 0.6 mSv and the effective collective doses were 24 man·Sv and 20 man·Sv, respectively, for these species. For the remainder, because of both their low consumption rates and low specific activities, the corresponding doses were negligible compared with the former.
Uranium (U) and thorium (Th) isotopes and their several radioactive descendants found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. Phosphate rocks are really rich natural sources of uranium and thorium among the other minerals forming the earth's crust. U and Th concentrations in some Egyptian phosphate samples were determined using a nuclear track registration methodology and -ray spectroscopy. The resulting latent tracks from all -decaying isotopes in both U and Th series were recorded in plastic detectors. A uniquely sensitive polycarbonate CR-39 nuclear detector was used. Results showed that the U and Th concentration in the samples studied range from about 4.0 up to 35.0 ppm and from 11.0 to 124.0 ppm, respectively. Results are discussed within the frame work of track formation methodology in plastic and -ray spectroscopic analysis.
Uranium (238U) and thorium (232Th) concentrations were evaluated in different cereal, fruit and vegetable samples by using a method based on the calculation of the detection efficiencies of the emitted a-particles by CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and measuring the resulting track densities. The influence of the soils on which the plants grow, and the fertilizers used was investigated. Total daily intakes of 238U and 232Th for a typical food basket were estimated to be 1.16 Bq.d-1 and 0.94 Bq.d-1, respectively, corresponding to a total committed effective dose of 0.27.10-7 Sv.d-1. Annual committed effective doses due to 238U and 232Th originated from the ingestion of different foodstuffs were evaluated for the adult members of the population by using the ICRP ingestion dose coefficients.
Authors:R. Sivakumar, S. Selvasekarapandian, N. Mugunthamanikand, and V.M. Raghunath
Indoor natural radiation dose existing in dwellings of Coonoor have been estimated using thermoluminescent dosimeters. TLDs are displayed in indoors and are replaced after three-month period. The seasonal averages of the dose rate and the annual effective dose equivalent are calculated from the measured results. Geographical and seasonal variations as well as the differences between indoor to outdoor dose rates have also been studied. Very good correlation exists between the indoor dose rates measured by TLD and environmental radiation dosimeter with correlation coefficient of 0.91. The annual effective dose equivalent to the Coonoor population due to indoor gamma radiation was estimated to be 970 mSv/y for the period of 1997–1998.
Authors:J. Zaidi, M. Arif, I. Fatima, and I. Qureshi
Extensive use of pan, by one-tenth of world"s population, entails the evaluation of trace element contents in its ingredients. Radiochemical neutron activation analysis (RNAA) was developed and successfully employed to determine the concentration of 36 trace elements (essential, toxic and nonessential) in its four basic ingredients, leaf of betel pepper, betel nut, catechu and lime. The radiochemical separation methodology has significantly improved the detection limits of most of these elements due to suppression of Compton background. This study provides the base-line values of certain toxic and essential elements in these ingredients. The daily intake of essential and toxic elements through pan was estimated and compared with the recommended values. The cumulative intake of Mn is four times higher than the recommended value and that of toxic elements is well below the tolerance limits.